Electronic circuits, when they are operating, produce heat. This heat is not used and must be removed in order to avoid deteriorating the circuits. Other sources of heat are also present in our environment, such as for example conduits, exhaust, the walls of industrial machines, etc., of which the heat given off is not used.
It is considered to recover this heat in order to convert it into electrical energy.
It is for example considered to use bimetallic strips, the latter are formed of two strips of different metals, materials or alloys with different coefficients of expansion, flexible, welded or glued to one another, in the lengthwise direction. Due to the different coefficients of expansion of the two strips, the bimetallic strips are deformed with a large amplitude when it is heated as well as when it is cooled. When it is heated, the latter switches from a substantially flat shape to a shape having a certain curvature. The orientation of the curvature depends on the temperature to which it is subjected, and the initial properties of the material (thickness, coefficients of thermal expansion, etc.). This deformation is converted into electrical energy by a transducer, for example a piezoelectric material which is deformed or shocked when the bimetallic strip becomes curved. The energy transmitted to the piezoelectric material, and therefore the energy recovered are not optimal.
There are also preformed bimetallic strips that have a first and a second stable state according to the temperature they are subjected to. In each of the stable states, they have a curvature or deformation, with the curvatures or deformations of the two stable states being opposite in most cases. These bimetallic strips are also designated as “blistering bimetallic strips”. When such bimetallic strips are heated and switch from a first stable state to a second stable state, this is referred to as “blistering”, and when the bimetallic strips are cooled, and switch from the second stable state to the first stable state, this is referred to as unblistering. During the blistering and the unblistering, a large quantity of energy is released.